This invention relates to arc welding devices provided with vacuum fume extraction means. This invention particularly relates to arc welding guns provided with vacuum fume extraction means including means for regulating the level of vacuum at the fume intake port of the fume extraction device.
The fumes generated in gas shielded metal and gasless metal are welding of various substrates constitute both a health and visual problem for the welders. The welding industry has actively been pursuing improved ventilation systems including adapting various welding fume extractors directly to the welding gun itself. Typically, such fume extractors include vacuum fume extraction means exemplified by those described in U.S. Ser. No 107,097 filed Jan. 1, 1971, and its Continuation Ser. No. 354,193 filed Apr. 25, 1973, of common assignment herewith.
While these vacuum fume extraction means have been generally successful, it has been found that under certain operating conditions their use has interfered with the welding operation. For example, in gas-shielded arc welding the shielding gas delivered to the head portion of the welding gun is occasionally extracted along with the product welding fumes when an excessively high level of vacuum is provided by the vacuum fume extraction means. The shielding gas thus becomes less effective in isolating the welding zone from atmospheric contamination, and the resultant welds suffer from undue porosity. Properly proportioning the amount of fumes extracted relative to the amount of shielding gas delivered becomes even more difficult when the welding zone is in a confined area. Prior art welding guns with vacuum fume extraction means have typically provided only one level of vacuum, and as the guns have been operated in various working positions, the weld rate and quality of the welds have been frequently adversely affected.
It is therefore an object of this invention to provide vacuum fume extraction means, including regulating means, for use in conjunction with arc welding guns.
It is a further object of this invention to provide means for regulating the vacuum level of vacuum fume extraction means for arc welding guns.
It is an additional object of this invention to provide an arc welding gun having vacuum fume extraction means whereby the vacuum may be regulated to extract fumes during gas-shielded arc welding operations without substantially interfering with the protective function of the shielding gas.
It is another object of the invention to provide an arc welding gun having fume extraction means, including regulating means, whereby improved welds will be obtained from gas-shielded welding operations in confined area.